Battery plates having rounded lower corners

Abstract

A process for cutting a moving strip to form a series of plates, such as battery plates, includes the initial step of transporting the strip past a rotary divider including a cutter having radial blades configured to cut the strip into the plates. The cutter further has a set of blades for cutting individual pieces from the strip, which pieces are not part of the plates. As the cutter blades cut the strip to form the plates and pieces, a vacuum system applies suction to draw the pieces cut from the strip inwardly into the cutter through holes in the cutter, and then out of the cutter. The holes are each located adjacent each one of the corresponding blades and are shaped and positioned to permit the cut-away piece to pass through. In a preferred embodiment, the vacuum system includes a pair of vacuum manifolds that apply suction at opposite ends of the cylindrical cutter. An apparatus for carrying out the foregoing process accordingly includes a rotary divider as described above provided with a vacuum system. Battery plates made according to the foregoing process are improved in that the two lower corners have a rounded shape lacking a sharp edge which tends to tear an adjacent separator. Such a plate may be inserted bottom end first into a separator envelope to form a plate element for use in a lead-acid battery.

We claim: 
     
       1. In a battery plate for use in a lead-acid battery, the plate comprising a conductive grid covered with an active lead material, the grid comprising a generally rectangular outer frame having a pair of sides, a top and a bottom spanned by grid elements forming a mesh, the frame having a pair of upper corners, a pair of lower corners, and an electrically conductive tab extending from a location on the top of the frame between the two upper corners, the improvement which comprises: the plate has been formed by expanding a strip of lead alloy, and the two upper corners are square and the two lower corners have a rounded shape lacking a sharp edge which would tend to cut an adjacent separator element, and the sides of the frame are substantially straight and free of projections.   
     
     
       2. A plate element for use in a lead-acid battery, comprising: a separator envelope joined along its sides and bottom end and having an open upper end; and   a battery plate comprising a conductive grid formed by expanding a strip of lead alloy and having an active lead material applied thereto, which plate is inserted into the separator envelope bottom end first, wherein the grid comprises a generally rectangular outer frame having a pair of sides, a top and a bottom spanned by grid elements forming a mesh, the frame having a pair of upper corners and a pair of lower corners, with an electrically conductive tab extending from a location on the top of the frame, the plate being substantially completely inserted into and covered by the envelope except for the tab, which extends out of the open upper end of the envelope, and the two lower corners of the plate have a rounded shape lacking a sharp edge which would tend to cut the separator envelope.   
     
     
       3. The plate of claim 1, wherein the tab extends from a location between and spaced from the two upper corners. 
     
     
       4. The plate element of claim 2, wherein the upper corners of the frame are square. 
     
     
       5. The plate element of claim 4, wherein the sides of the frame are substantially straight and free of projections. 
     
     
       6. The plate element of claim 2, wherein the separator envelope has substantially the same shape as the frame and is sealed along its bottom and sides so that the frame fits closely therein with the tab projecting out of the open upper end of the separator envelope. 
     
     
       7. The plate element of claim 6, wherein the separator envelope consists essentially of polyethylene. 
     
     
       8. The plate element of claim 7, wherein the separator envelope consists essentially of a single piece of polyethylene folded in half along a bottom edge thereof and crimped along its sides. 
     
     
       9. The plate element of claim 4, wherein the tab extends from a location between and spaced from the two upper corners.